206 METHODS OF COMMUNICATION FOR FOREST PROTECTION 



und'er no consideration be placed less 'than 12 ft. from the rail of a main line, or less 

 than 6 ft. from the rail of a siding. At loading sidings sufficient space to te left 

 for driveway. 



D Setting and strength of poles. Poles less than 50 ft. in length to be set not 

 less than 6 ft. and poles over 50 ft. not less than 7 ft. i-n solid ground. Poles with 

 side strains to be reinforced with braces and guy wires. Poles to be at least 7 in. 

 in diameter at the top mountain cedar poles to be at least 8 in. at the top. In 

 soft ground poles must be set so ,as to obtain the same amount of rigidity as would 

 be obtained by the above specifications for setting poles iii solid ground. When the 

 line is located in a section of the country where grass or other fires might burn them, 

 wooden poles to be covered with a layer of some satisfactory fire-resisting material, 

 such as concrete at least two in. thick, extending from the butt of the pole for a 

 distance of at least 5 ft. above the level of the ground. Wooden structures to have 

 a safety factor of 5. 



E Setting and strength of other structures. Towers or other structures to be 

 firmly set upon stone, metal, concrete or pile footings or foundations. Metal and 

 concrete structures to have a safety factor of 4. 



E Length of Span. Span must be as short as possible consistent with the rules 

 of setting and locating of poles and towers. 



G Fittings of wooden poles for telegraph, telephone, or similar low-tension lines. 

 The poles at each side of a railway must be fitted with double cross-arms', dimensions 

 not less than 3 in. by 4 in., each equipped with 1^-in. hardwood pins, nailed in arms, 

 or some stronger support and with suitable insulators; cross-arms to be securely 

 fastened to the pole in a gain by not less than a f-in. bolt through the pole; arms 

 carryiiig more than two wires or carrying cable must be braced by two stiff iron or 

 substantial wood braces fastened to the arms by --in. or larger bolts, and to the pole 

 by a f-in or. larger bolt. 



H Fittings of all poles, towers, or other structures. All wire-supporting structures 

 to be equipped with fittings satisfactory to the Engineer of the Board. 



I Guards. Where cross-arms are used, an iron hook guard to be placed on the 

 ends of and securely bolted to each. The hooks shall be so placed as to engage the 

 wire in the event of the latter's detachment from the insulators. 



J Insulators. All wires or conductors for the transmission of electrical energy 

 along or across a railway to be supported by and securely attached to suitable insula- 

 tors. 



Wires or conductors in 10,000-volt (or higher) circuits, to be supported by insula- 

 tors capable of withstanding tests of two and one-half times the maximum voltage to 

 be employed under operating conditions. An affidavit describing the tests to which 

 the insulators have been subjected and the apparatus employed in the tests shall be 

 supplied by the applicant. The tests upon which reports are required are as follows: 



Ja Puncture or rupture test. The insulators having been immersed in water for 

 a period of seven days, immediately preceding and ending at the time of the test, to 

 be subject for a period of five minutes to a potential of two aiid one-half (2-5) times 

 the maximum potential of the line upon which they are to.be installed. 



Jb Flash-over test. State the potentials that were employed to cause arcing or 

 flashing across the surface of the insulator between the conductor and the insulator's 

 point of support when the surface was (1) dry, and (2) wet. 



K Height of wires (a) Low-tension conductors. The lowest conductor must not 

 be less than 25 ft. from top of rail for spans up to 145 ft.; 2 ft. additional clearance 



